Creating the Flu Vaccine

No more “strain”ing to keep up

By Ben Brody

Inside a laboratory on the campus of New York Medical College in Valhalla, Doris Bucher, PhD, is helping to eradicate a deadly viral epidemic. Every year in the United States alone, the virus Bucher is fighting sends 200,000 people to the hospital. In the past, it may have killed as many as 100 million in a single year and still routinely takes 25,000 to 50,000 lives at a swipe.

The virus is influenza, but, thanks to Bucher’s 10-person lab, 400 million doses of vaccine are available to combat the virus every year.

Bucher’s contribution is the solving of a major problem in vaccine manufacture. Scientists are good at keeping track of influenza viruses and figuring out which of their many variants (U.S. labs logged about 350 subtypes in 2010 alone) will become the dominant strain of the season. What’s difficult, however, is getting the dominant strains to reproduce diligently inside eggs, as vaccine manufacturers need them to do.

That’s where Bucher’s lab comes in. The lab keeps a wizened influenza isolate from 1934 that is “highly adapted and so happy to grow in eggs.” She uses its 1934 strain and the upcoming season’s strain to make hybrid viruses that look to our immune systems like the upcoming season’s strain (so that our bodies can learn to fight it off), but also have all that good “this egg looks homey; I think I’ll make some offspring” pluck that the manufacturers need to turn a “seed virus” into millions of doses.
As of this writing, the World Health Organization—which predicts which strain will be dominant—has not indicated what strains they think should be used in vaccines for this year’s flu season (which will begin in the fall). “That’s the thing about flu: it’s a tricky virus,” says Bucher of potential changes. Still, since the 2010 southern hemisphere season (which began in spring 2010), the WHO has been recommending the same vaccine each season in both the northern and southern hemispheres, and Bucher’s lab created the seed for all three of its components. So, don’t worry: even if a new strain pops up, it may well be that Bucher and her team will be making the seed for that too.